Recently, all electronic components including a capacitor have been urgently required to be downsized and increased in performance. Capacity of the capacitor is proportional to an area of an electrode plate and is inversely proportional to a distance between electrodes. At this time, a thickness of a dielectric is equal to the distance between the electrodes. When dielectrics have the same dielectric constant, for increasing the capacity of the capacitor, the area of the electrode plate needs to be increased or the dielectric layer needs to be thinned. In other words, for downsizing the capacitor and simultaneously maintaining or increasing the capacity thereof, it is effective to thin the dielectric layer and increase an effective area of the electrode plate. As a laminated body that is formed of the dielectric layer and the metal thin film layer and is used in the capacitor or the like, a film capacitor is known. Structure of the film capacitor is described below. A metal thin film made of aluminum or the like is firstly formed on a resin film in during vacuum deposition method or a sputtering method. The resin film is made of polyester (for example, PEN or PET), polyolefin (for example, PP), or PPS. Metal thin films manufactured from such a method are laminated or wound, thereby forming a film capacitor. The resin film functions as a dielectric. In this case, constraint in manufacturing the film limits thinning of the resin film. A minimum thickness of a film for a presently used film capacitor is about 1.2 μm. For further capacity of the capacitor, an effective area of the dielectric needs to be increased, namely a number of laminations and a number of turns need to be increased. However, simultaneous downsizing and capacity increase of the film capacitor causes a limit to be reached. U.S. Pat. No. 5,125,138 discloses a multi-layer capacitor in which a laminated body is formed of a dielectric layer and a metal thin film layer, with a thickness of the dielectric layer being about 1 μm. The dielectric layer is formed by polymerizing a reactive monomer. Japanese Patent Unexamined Publication No. H11-147279 discloses a chip capacitor having a dielectric layer formed by polymerizing a reactive monomer. FIG. 6 is a sectional view showing a structure of a conventional multi-layer chip capacitor.
In FIG. 6, internal electrodes 11 and dielectric layers 12 are sequentially laminated, and electrical insulation part 13 exists in each internal electrode 11 every two layers. External electrodes 41 are finally formed to constitute a multi-layer chip capacitor as a product. Electrical insulation parts 13 are provided for forming a capacitor. Electrical insulation parts 13 function for preventing a short circuit and increasing an effective area of dielectrics in a capacitor forming part.
Electrical insulation parts 13 have no metal layer, so that uneven parts occur in the capacitor in response to an increase of a number of layers. This state is shown in the enlarged view of electrical insulation parts 13 of FIG. 7. When the number of layers exceeds 1000, electrical insulation parts 13 can be deeply recessed as shown in FIG. 8. In such a case, each internal electrode 11 is disconnected or internal electrodes 11 are short-circuited, thereby damaging function as a capacitor. This problem can be further noticeable when a thickness of the dielectric layers is decreased to a thickness unachievable in a conventional film capacitor. The present invention aims to essentially address the problem occurring in achieving downsizing or high capacity of a capacitor. An improvement of productivity is also one purpose of the present invention.